洞庭湖不同水位高程下南荻(Triarrhena lutarioriparia)种群分布格局及生长动态

Population distribution patterns and growing status of Triarrhena lutarioriparia along a gentle elevation gradient of Lake Dongting wetlands

通过野外不同水位高程固定样地多次调查,结合方差/均值比率法研究了不同水位高程下洞庭湖湿地南荻(Triarrhena lutarioriparia)种群分布格局及生长动态.结果表明:(1)低程区土壤含水量显著高于高程区;低程区土壤颗粒组成与高程区相比有显著差异,低程区土壤为黏砂壤土,高程区为粉砂土;低程区土壤总有机碳、全氮、铵态氮和pH值等与高程区相比无显著差异,而其硝态氮、有效磷、全钾和速效钾含量低于高程区,全磷含量却恰好相反.(2)调查期间,南荻的分布格局随着植物的生长由均匀分布逐渐变为聚集分布,低程区聚集强度更大;(3)南荻的生物量和高度均随时间增长而迅速增加,且低程区的总生物量和增长量均高于高程区;南荻的密度和基径随时间增长而增加,之后趋于平稳,且低程区均高于高程区.结果分析表明,水位高程差异引起的土壤含水量的显著变化可能是影响南荻分布格局和生长动态最重要的因素.因此,适度地调控水位、增加土壤水分含量可能是控制南荻群落扩张的重要措施.

In this study, the population distribution patterns and growing status of Triarrhena lutarioriparia along a gentle elevation gradient were analyzed based on an investigation of the fixed quadrat plot and a method of variance to mean ratio in a typical beach of Lake Dongting wetlands. The results indicated that （ 1 ） soil moisture content was significantly higher in the low altitude areas than in the high altitude areas. Soil particle composition of low altitude areas was significantly different from that of high altitude ar- eas. Soil pH was all alkaline. There was also no significant difference in soil total organic carbon, total nitrogen, ammonium nitrogen content and pH, while soil nitrate nitrogen content in low altitude areas was significantly lower than that in the high altitude areas. Soil total phosphorus content was significantly lower in high altitude than that in low altitude, while available phosphorus, total potassium and available potassium showed opposite patterns. （2） The population distribution patterns of T. lutarioriparia in both low and high altitude areas were all changed from a uniform distribution to an aggregated pattern, while the aggregation intensity was greater in the low altitude areas. （3） The biomass of T. lutarioriparia accumulated rapidly along with the time going, which was significantly lower in the low altitude areas than in the high areas. Density and basal diameter of T. lutarioriparia increased significantly along with the time going, which were higher in the low altitude areas than in the high altitude areas. These results indicated that the soil moisture content had a significant influence on the population distribution patterns and the status of T. lutarioriparia growing. Therefore, moderate regulating of water level and increasing soil moisture content may be adaptive to control the invasion of T. lutarioriparia into the Carex community.